1. Field of the Invention
The invention relates to a driving assistance technique.
2. Description of Related Art
There is known a driving assistance apparatus that detects an obstacle around a host vehicle by obstacle detecting means, and the like (for example, an ultrasonic sensor or a millimeter wave radar) and that avoids a collision with the obstacle. The driving assistance apparatus mostly avoids a collision with an obstacle by executing interventional control for suppressing driving force of the host vehicle or generating braking force (see Japanese Patent Application Publication No. 2011-122607 (JP 2011-122607 A) and Japanese Patent Application Publication No. 2012-061932 (JP 2012-061932 A)).
After a collision with an obstacle is avoided by the driving assistance apparatus, for example, if the driving force suppressed by interventional control is returned, a limitation may be placed on a manner of returning the driving force in terms of safety because there is a high possibility that the obstacle is still present around the host vehicle (see JP 2011-122607 A and JP 2012-061932 A).
For example, a vehicle control system described in JP 2011-122607 A cancels driving force suppression control when a vehicle speed is higher than or equal to a predetermined value. A collision avoidance system described in JP 2012-061932 A causes an engine driving force not to increase beyond a preset limit driving force when the collision avoidance system determines that a collision with an obstacle has been avoided.
Incidentally, there is a case where snow, or the like, adheres to obstacle detecting means, such as an ultrasonic sensor, the obstacle detecting means erroneously detects the adhesion matter as an obstacle, and driving assistance is started for avoiding a collision. In this case, there is no obstacle around the host vehicle and driving assistance for avoiding a collision is not required, so driving assistance for avoiding a collision is cancelled, and, for example, it is required to reduce a feeling of strangeness experienced by a driver by early returning the driving force suppressed through interventional control.
However, in the case of a return of the driving force after the adhesion matter to the obstacle detecting means has been erroneously detected as the obstacle, if a limitation is placed as described in JP 2011-122607 A or JP 2012-061932 A, a desired acceleration is not obtained although there is no obstacle around the host vehicle, so the driver may experience a feeling of strangeness or a discomfort.